Compressional wave transmitting and receiving apparatus



06%. 1, 33. BATCHELDER 2,408,404

COMPRESSIONAL WAVE TRANSMITTING AND RECEIVING APPARATUS Original FiledMay 19, 1933 Patented Oct. 1, 1946 CDMPRESSIONAL WAVE TRANSMITTING AND:RECEIVING APPARATUS Laurence Batcheld'er, Cambridge, Mass, assignor,

by mesne assignments, to Submarine Signal Company, Boston, Mass, acorporation "of De'l'aware Original application May 19., 671,870..Divided and this. 13, '1'9'34',v Serial No. 715,349;

ber 19,1938.

1933, .Serial. No. application Marchv Renewed Septem- Claims. (Cl.177-386) The present application is a division of my copendingapplication filed May '19, 1933, Serial No. 671,870, Patent Number2,380,931.

The present invention relates to apparatus for producing compressionalwaves and is applicable for the production of such waves in air, wateror in other media.

In the present invention the compressional waves produced are moreparticularly in the range of so-called supersonic frequencies, that is,frequencies which are beyond the audibility of the human ear, althoughto some extent the present invention is also applicable to theproduction of high-frequency compressional or sound waves which aresituated in the upper part of the audibility range of the human ear andjust beyond it.

Due to the fact that metals possess great elasticity and that the wavelengths of high frequency compressional waves are very short in metals,it is difilcult to assume that the masses involved in compressional-waveapparatus of this type move as masses alone without partaking in thevibration of the vibrating elements.

In the prior art devices have been used in which a radiating surface orarea was very large as compared with the wave lengthof the sound to bepropagated in the propagating medium and the radiating surface wasvibrated at a plurality of points in order to produce aplane wave or adirected beam of sound or compressional Waves. Such devices have beenusefully employed both in so-called piezo-electric oscillators and inoscillators of the magnetic type.

In supersonic oscillators of the piezo-electric' type a mosaic ofpiezo-electric crystals are mounted between steel plates. The thicknessof the plates together with that of the crystals are such as toestablish a tuning in a direction perpendicular to the plate surfaceand, each crystal, in fact, vibrates that part of the plate where it. isattached. An examination of this type of. oscillator indicates that thewhole plate does not move with the same amplitude and that between theplaces Where the crystals are applied the vibrational energy issometimes quite small.

In other types of oscillators the same characteristics are found andwhile it is possible to pro-- time some vibration over an entire plate,it has been found a fact that the vibration is more particularlyproduced opposite the places where the vibrational energy is applied.This gives evidence of the fact that in high frequencies there isdiiiiculty in making a plate act as a diaphragm and the tendency is forit simply to act as a transmitting medium.

In devices employing other than piers-electric means, for instance; inoscillators of "the :magnetosh'ictive type, itis possible to useresonant tubes or rods for driving a sound diaphragm over its surfaceinthe same phase. The dilficu lty', however, of making the wholediaphragm or plate to which the rod'sare attached vibrate isalso presenthere, and is is usually-observed that the vibration occurs morepa-rticularly' at the points where the rods 0r tubes, producing thecompressional wave energy, are attached.

I have "also observed that it is quite impossible to predict just howsuch-"plates or diaphragms will vibrate and just what load eitherradiating or mass load should be considered as belonging to eac'hoperating unit. In fact, itsappears that rods ortubes similarlyattachedwhich beforehand had the same resonant frequencies may well afterattaching have other resonant frequencies. Tl-us fact alone makes itdifficult tonbtain a uniform resonance of all the operating andseriously handicaps and limits the available power output, since someunits are operating on resonance whileother-un-its are off the resonantpoint. condition also distorts the soundbeam-sinceitis-apt to destroythe. uniform 'phasevi'bration of the entire vibrating surface.

In the present system which I have devised I have avoided may -ofthesediificulties by con-- structing-each unit as an independently operatingunit and establishing the same resonance point for each so that they canall operatewith the same amplitude in the same phase at the samefrequency; In order" to produce a fixed beam of compressional waves itisonly necessary in the'present system to have a s-ufliciently largenumber or independently operating units positioned or'nested closetogether vibrating the same phase in order to produce a plane wave whosewidth in the propagating medium will-be many times the wave len-gth ofthe sound or c0mpressi'onal wave produced;

When it-is desired to produce a directive beamof sounder compressionalwaves whose direction can be controlled or varied, this may be done-byvibrating lines or groups-hf individually spent-- ing units with properphase-differences, it being preferable under such conditions to havethem-'- dividuallyoperatingunits-relatively point sources so that eachpoint in the medium may have the right vibrational phase.

Figure I shows a fragmentary section through the oscillator showing therows. of oscillating ele ments; Figure 2 shows a sectional view oi themodification shown in Figure 1 taken on the line 2-2 of Figure 1; Figure3 shows a perspective of a detail'fof the same modification; Figure-i 4shows afurther modification on the same type ofview as indicated inFigure section along the line 5-5 of Figure 4; and Fig-" ure 6 shows afragmentary perspective of a de-.

tail of the same modification.

In the present application which is a division of the applicant'scopending case, as stated above, the structure more particularlydescribed and claimed is one in which a group of long flat plates makeup the radiating unit. These may be assembled together very closely withthe center lines of the units substantially a half wave length apart oreven less or they ma what wider in construction, depending upon theparticular method in which it is desired to.op-

erate the units. Where the units are wider than ahalf wave length, eachtobecome directive and therefore such a construction should not be usedunless it is desired to'transmit a beam in a direction normal to thesurface, of. the radiating units. Regardless of which type maybeiemployed, the-principles set forth in the presentconstruction applyto the operation of the elements as long fiat plates operated by stripsthat are resonant with the plates longitudinally in the direction of thewidth of the strips.

The invention is illustrated in Figures 1, 2 and 3. In Fig. 1 themagnetostrictive element comprises an elongated strip I which has aradiating unit H made integral with the end thereof. The, radiating unitII is elongated, as indicated in Fig. 3, and may be constructed withinclined shoulders 12. The magnetostrictive strip I0 may be providedwith slots I3 as indicated by the dotted lines in Fig. 2. The lower endof the strip I0 is held between similar magnetizable plates I4 and Imade up of C-shapedlaminations and thus when assembled are recessed tocontain the coil I6 which, as indicated in Fig. 3, is elongated andsurroundsthe strip I0. At the lower end of the plate there is provided aplurality of flat head screws I1 which pass from one plate into theopposite plate and thereby clamp rigidly the end of the magnetostrictivestrip 10. This furnishes a clamping mass for the magnetostrictive strip10 which vibrates in its vertical dimension as shown in Fig. 1, and hasa resonance of vibration normal to the efiective radiating plane of theunit H.

The plates I4 poles I8 shaped to conform to the inclined surface 13underneath the top of the radiating element I I. In this manner thecomplete magnetic path for the coil 16 is through the strip 10 about thesurrounding plates I4 and I5 and returning through the small air gap atthe sides and underneath of the radiating plate I I.

The units indicated in Fig. 1 are in themselves independent and maypreferably .be made of considerable length many times the wave length ofthe compressional wave which it is desired to generate in thesound-propagating: medium. Each of these units maybe arranged to form--parallel successive rows and a greatnumberof the units maybe used sothat the horizontal di mension of the device may be many times-the wavelength of the sound produced in the propagating medium. In such anarrangement each unit will be vertically disposed and if they areindependently eXGitQQ desired phase difierupon the distance of the unitsences'depending 2; Figure 5 shows a y be made someindividual unit tendsand I5 have upper projecting from each other and the wave length of thesound to be generated, a beam effect will be obtained. In themodification shown in Fig. 1 the units themselves may be mounted in alarge base 5 plate 90 to which they are held by means of the screws 9|.The units may individually be made watertight by providing the plates 14and 15 and also the radiating end II with a proper groove 92 in whichthe gasket 93 might be placed to prevent water from entering into andaround the coil. This watertight gasket can also serve to center andspace the radiating unit 1I so that no sideways motion will be present.A row of screws 94 is provided at the end of each unit so that the unitsmay be firmly clamped both at the top and along the sides.

In the unit shown in Figs. 1, 2 and 3 a s'olid'structure is illustrated.

In Figs.' l, 5 and 6 part of the structure is laminated. In thismodification the end-radiating element I00 and the strip IOI may bebuilt up of a series of laminations which are held tight at the top by abolt I05 passing completely through the whole group of laminations orthis element in itself may be of a solid structure. The lower end of thestrip IUI is clamped between clamping plates I02 and I03 which arefirmly screwed together by means of the screws I04.

The coil I00 corresponding to the coil I6 of Fig. l is encased by acover built up of laminations I01 which are held together by means ofthe stay rods I08, I08, etc. The laminations I0'I are built up in groupsbetween which are the supporting members I09, I09, etc., through whichthe rods I08 also pass making a substantially rigid structure anduniting the laminations together in plates equivalent to the side platesI4 and I5 of Fig. 1. The members I09 extend downward below thelaminations and rest in corners in the clamping blocks I02 and I03 towhich they are held by means of the screws H0. The end radiating elementI00 may be covered by means of a rubber cover III which may be cementedto it and also cemented to the casing H3 at the shoulder II l. As willbe seen in Fig. 4, the oscillator is built up of a number of parallelunits in which the radiating elements run substantiallyparallel. Itshould be noted that in this modification as well as in the structureshown in Figs. 1, 2 and 3 that the individual units are long as comparedwith the wave length of the wave transmitted in the propagating medium,and the length of the unit itself may be of a difierent order ofmagnitude than the wave length of the transmitting wave.

It should also be noted that the effective radiating length of the wholeoscillator may also be many times the wave length of the wavetransmitted, in which case a considerable number of I individual unitswill go to make up the entire oscillator.

In Fig. 6 is shown a perspective view of the modifications shown inFigs. 4 and 5. In this view the structure at the end of the oscillatoris more clearly indicated. It will be noted that the corner which fitsat the end of the last laminated group is composed of two pieces I I5and I I6 which are themselves unjoined, being held to the laminatedstructure by means of the stay rods I08 as explained above.

Having now described my invention, I claim:

1. Means for producing a beam of compressional waves comprising aplurality of parallel elongated plates having magnetostrictive strips 7attached to the same, means including said magnetostrictive strips forvibrating said plates at the desired frequency, means clamping saidstrips at the ends opposite the plates, said strip being tuned toresonance for the desired frequency of vibrations transverse to the longdimension of the strip.

2. Means for" producing a beam of compressional waves comprising aplurality of parallel elongated radiators having magnetostrictivestripsatt'ached to the same, means including an energizing coil and saidmagnetostrictive strips for vibrating said plates at the desiredfrequency, a plurality of elongatedplates positioned parallel to saidstrips and having projecting elements at the ends thereof, said platesbeing composed of magnetic material and serving "as the return magneticpath for the flux passing through the magnetostrictive strips to.provide. clamping surface at the lower ends of said stripsfeach of saidstrips being tuned to resonance for said desired vibrations normal tosaid radiators.

3. Means for producing a beam of compressional wave comprising aplurality of parallel elongated radiators having magnetostrictive stripsattached to and vibrating the same, an elongated coil surrounding eachof said strips, a plurality of elongated plates of magnetic materialpositioned parallel to said strips and having portions projectingtherefrom near the ends towards said strips, said projecting portionsserving to provide clamping surfaces and said plates serving as thereturn magnetic path, means cooperating with said plates for clampingthe lower ends of said strips thereto, each strip being tuned toresonance for vibrations normal to the radiators and each coil adaptedto be independently connected to a separate supply source.

4. Means for producing a beam of compressional Waves comprising aplurality of parallel elongated magnetostrictive strips having radiatingmeans on a corresponding long edge of each,

- and being tuned to resonance for vibration normal to the radiatingmeans, elongated coils each surrounding one of said strips, a pluralityof elongated plates of magnetic material having portions projecting atthe ends thereof and completing a return magnetic path for said coilsenclosed by the plates and said projecting portions, means clamping thestrips between plates at one set of projecting portions and meansholding said plates together in parallel relation.

5. Means for producing a beam of compressional waves comprising aplurality of parallel magnetostrictive strips elongated in one dimensionand resonant to the frequency desired to be produced in the widthdimension, said strips having radiating means fixed on a correspondingedge of each, and being tuned to resonance for vibrations normal to theradiating means, an elongated coil surrounding each of said strips, aplurality of elongated plates of magnetic material having a recessedportion shaped to conform on one side to the contour of said coil andfur nishing a return magnetic path for the flux generated by said coiland passing through said strips, means including said plates forclamping the strips between said plates at the ends thereof and meansholding together said plates in parallel relation.

6. Means for producing a beam of c0mpressional waves comprising aplurality of wave radiators associated together in a unitary device,each radiator having a vibrating unit having a T- shaped section, a coilsurrounding the stem thereof, means of magnetic material clamping thelower end of the stem of the T, means of magnetic material includingsaid clamping means for completing the magnetic circuit from the end ofthe stem to the cross piece of the T, and a -soft rubber diaphragmcovering the radiating surface of the unitary device.

7. Means for producing a beam of compressional waves comprising aplurality of 'wave radiators associated together in a unitary device,each radiator having a vibrating unit having a T'- shaped section, acoil surrounding the stem thereof, means clamping the lower end ofthe-stem of the T, said means including means of magnetic materialexternal of the coil for completing-the magnetic circuit to' the topcross piece of the T and means between the ends of the cross piece-cfthe T and the magnetic means tocomplete closure of the coil and positionthe T-s'haped piece.

8. Means for producing a beam of compressional waves comprising aplurality of parallel elongated plates, said plates being arranged sideby side with their surfaces forming a continued plane surface, strips ofmagnetostrictive material attached to and supporting said plates,electromagnetic means surrounding each of said strips for energizing thesame, each of said plates being free to vibrate as a single pistonelement.

9. Means for producing compressional waves of high frequency comprisinga rectangular elongated plate, a strip of magnetostrictive materialsupporting said plate substantially along the middle of the same, anelongated coil positioned about said strip, a plurality of side elementsof magnetic material, said elements being provided with extendingflanges extending over the top and bottom of said coil and furnishing atthe bottom end a clamping surface for the bottom of saidmagnetostrictive strip and means clamping said plates and stripstogether at the bottom end thereof.

10. Means for producing compressional waves of high frequency comprisinga rectangular elongated radiator, magnetostrictive means for drivingsaid radiator, means forming an enclosed casing about saidmagnetostrictive means, said means providing a surface extending in thesame plane as said radiator and means carried between said radiator andsaid casing for producing a watertight joint between the same.

11. Means for producing compressional waves of high frequency comprisingan elongated rectangular radiator having one side flat and the oppositeside tapered to form a V-shaped section, means forming a groove at theside of said radiator, means for driving said radiator simultaneouslyover its whole length, magnetic mean forming a casing about said drivingmeans, said means being provided with a groove opposite said groove insaid radiator and means extending between said grooves for providing awater-tight joint Within said casing.

12. In a means for producing a beam of compressional waves, a radiatingelement having a T-shaped section formed of a plurality of T- shapedlaminated strips having means binding said strips into said T-shapedsection, coil means for impressing magnetic flux through the stem ofsaid T-shaped element, a plurality of substantially C-shaped laminationof magnetic material encasing said coil means and positioned to formpole elements for a magnetic circuit, the top and bottom horizontalportions of the 0 being positioned at the lower part of the stem and atthe cross bar portion of the T strips and means for holding saidlaminations in position adjacent said strips.

13. In a means for producing a beam of compressional waves, an elongatedradiating surface having magnetostrictive strip means formed as a partthereof running substantially the length of said surface, a plurality ofC-shaped magnetic pole elements positioned at the sides of said strip, acoil surrounding said strip, the top and bottom portions of the Cprojecting over the coil and means for holding said pole elements inposition against said strip at the lower end.

14.In a means for producing a beam of compressional waves, an elongatedradiating element having magnetostrictive strip means extendingsubstantially the length thereof and positioned symmetrical to thesection of the radiator, coil means surrounding said magnetostrictivestrip and providing electromagnetic flux for the same, means forclamping said strip at the bottom ineluding means of magnetic materialproviding a magnetic flux path having a pole face adjacent the radiatingelement at the top of the strip.

15. Means for producing a beam of compressional waves comprising a groupof parallelly arranged elongated radiators, strips of magnetostrictivematerial each supporting one of said radiators, means separating saidradiators one from the other providing surfaces opposed to one another,said means also having a surfacev in the extension of the same plane asthe radiators themselves and means supported between said radiators andsaid separating means for maintaining the surfaces of said separatingmeans and said radiators that are opposed to one another free fromcontact with each other.

LAURENCE BATCHELDER.

